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Depositional conditions controlling organic carbon burial in fine-grained sediments of the North Sea – The Helgoland Mud Area as a test field

Fine-grained marine sediments are the largest permanent carbon sink on our planet. We chose the Helgoland Mud Area (HMA) as it represents the most important depocenter of such sediments in the German Bight and hosts a variety of sedimentary habitats that differ in key depositional factors – including water depth, sedimentation rates, grain size and origin of organic matter (OM). The HMA serves as a natural model area to (1) identify the main depositional drivers controlling the burial of organic carbon and (2) assess the efficiency of different sedimentary habitats as natural long-term carbon sinks. During two expeditions with RV Heincke, we collected a total of 16 MUC-cores from different areas of the HMA. Pore-water and solid-phase sampling and analyses were performed - including 210Pbxs to assess sedimentation rates and bioturbation depths, grain-size distribution, TOC contents and pore-water concentrations and stable carbon isotopic composition of DIC to determine the origin of the degrading OM. Sedimentation rates for the past ~200 years range from <0.5 to 6 mm yr-1 with highest rates in the southern and central part of the HMA. TOC contents typically vary from 1 to 2 wt% with highest values in areas of highest sedimentation rates. The source and reactivity of the degraded OM show large variations, ranging from marine origin in the NW to terrestrial sources in the S of the HMA. The obtained data set will be subject to statistical analysis to determine the key factors controlling the burial of organic carbon in fine-grained North Sea sediments.

Details

Author
Daniel Mueller1, Bo Liu2, Walter Geibert2, Elda Miramontes3, Heidi Taubner3, Lasse Sander4, Moritz Holtappelsa5, Susann Henkel5, Ingrid Dohrmann2, Denise Bethke2, Jessica Volz2, Kai-Uwe Hinrichsb Hinrichs6, Sabine Kasten7
Institutionen
1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Germany;University of Bremen, Faculty of Geosciences, Germany; 2Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Germany; 3University of Bremen, Faculty of Geosciences, Germany;MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany; 4Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Wadden Sea Research Station, List/Sylt, Germany; 5Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Germany;MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany; 6University of Bremen, Faculty of Geosciences, Germany; 7Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Germany;University of Bremen, Faculty of Geosciences, Germany;MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany
Veranstaltung
GeoBerlin 2023
Datum
2023
DOI
10.48380/cf20-2592

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